In the world of software development, or any product, for that matter, one of the things you may frequently be asked to do is to create a “special version” for a specific consumer.  This version might be almost identical to something you have already created, but with a few minor tweaks, or it might need to share some of the same core characteristics but have critical deviations in certain areas.

For software development – and the correspondingly essential Configuration Management of that software – I’ve seen how this can be one of the more challenging aspects of the job.  It’s not actually the creation of the “customer-special” that’s difficult though; in fact this is usually fairly trivial.  Traditional software configuration management, or SCM, systems use the branch-per-variant approach typically, and everyone knows that branching is easy.  The hard part comes when you need to manage that customer release in an ongoing fashion.  How do you upgrade them to a newer release of your product?  They probably won’t want to remain on their baseline version forever.  They’ll want to take advantage of new features and fixes, while still retaining their unique aspects.  So this brings you to… oh yeah, the actual _merge_ part!  That’s where it gets hard.  Reliably merging changes from one variant to another is a manual, error-prone, labor-intensive process.  Now I remember!  That’s why we try to limit branching.

Configuration Management with Customer Specials

Well, all of that messy, cumbersome, and problematic stuff in traditional configuration management systems utilizes a traditional architecture of branches.  Fortunately, you use AccuRev, which completely removes this obstruction and makes the management of customer specials not only easy, but elegant as well.  Let’s consider the following purely mythical scenario.  A company called ‘Stadiums’ that makes Ballparks for general use releasedStadiums_Ballpark_2.0 a while back.  Stadiums had a customer who wanted a custom version of the Ballpark that had some significant differences.  For example, they had special contours to the outfield, a truly unique left-field wall, and a good old fashioned mechanical scoreboard.  Those were the changes that needed to be made which deviated from the core Ballpark.  So Stadiums made these changes in a dedicated stream, associated their work with issue records using AccuRev Change Packages, and cut the Stadiums_Ballpark_Fenway_1911 snapshot:

Fast forward a few years.  It’s been a while and there have been numerous advances in Stadiums’ technology.  Ballpark_4.0 has been released.  The Fenway people don’t want to purchase a brand new product, but they do want to upgrade. This is where it would get really complicated in a different configuration management tool. To boil it down, Stadiums would have to figure out what changes were made for Fenway back then, what changes have happened in their ongoing development, and intelligently merge these together.  They’d probably still want to maintain traceability and reproducibility of the “older” version of Fenway.  Some of the other tools out there make this near impossible, some slighly less onerous, but none of them make it simple.

Enter AccuRev.  Here’s what you do.  Drag the Stadiums_Ballpark_Fenway stream and drop it onto Stadiums_Ballpark_4.0.  That’s it, you’re almost done!  Because of Inheritance capabilities in AccuRev streams, all the content of Stadiums_Ballpark_4.0 will flow down into the _Fenwaystream… except items that are in conflict.  Those items will be identified by AccuRev both visually and with status flags, and you will be able to deal with them quickly and appropriately.

In our example, Stadiums developer llucchino has worked on the greenMonster.wall file and replaced class Netting with class monsterSeats.  So this file automatically becomes (overlap) in the_Fenway stream and can be merged.  There are more teams in the league so the scoreboard.mechanical file has been updated to change various properties.  This also is in (overlap) status.  But the contours of the outfield haven’t been updated at all, so despite that file being a custom modification for _Fenway, AccuRev intelligently knows that it doesn’t even need to be merged.  All other new content was automatically inherited by the stream, and so literally nothing needs to be done by the development team.

It’s that simple.  You’re done, go ahead and release Stadiums_Ballpark_Fenway_2011.  Another happy customer and it didn’t set you back many man months.  Can your configuration management tool do this?